Recent progress of PY-IT-based all-polymer solar cells

All-polymer solar cells (all-PSCs), with their specific merits of superior operation stability and remarkable mechanical flexibility, have made significant progress and become an indispensable part of the field of organic solar cells (OSCs) in recent years. This progress has established them as an indispensable component of the OSC landscape. One of the key driving forces behind this advancement is the development of high-performance polymer acceptor materials. Notably, the emergence of cutting-edge Y series polymerized small-molecule acceptors such as PY-IT, PYT, PY-2Cl, PY-V-γ, and PYF-T-o has significantly narrowed the efficiency gap when compared to the OSCs relying on small-molecule acceptors. Here, we systematically delve into the recent development of PY-IT-based OSCs. First, we offer a detailed discussion about the device physics of PY-IT-based OSCs and then illustrate their achievements from three aspects: binary systems, ternary systems, and layer-by-layer structures. Moreover, current challenges and outlooks are proposed for future research directions. We expect that our work will inspire further breakthroughs and improvements in the fields of all-PSCs.